#include <iostream>
int multirango(int n1,int n2);
using namespace std;
int main()
{
    int n1,n2;
    cin>>n1;
    cin>>n2;
    cout<<multirango(n1,n2);
    return 1;

}

int multirango(int n1,int n2)
{   int multi;
    multi=1;
    while(n1<=n2)
    {
        multi=multi*n1;
       n1++;

    }
return multi;

}
